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INTRODUCTORY OCEANOGRAPHY

Chapter 10 - Ocean Waves

Learning Objectives
Reading Assignment
Discussion
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Introduction

An introduction to this lesson

In this lesson we will explore the fascinating world of ocean waves. Our major emphasis will focus on waves generated by wind, from the smallest capillary waves ("ripples") to the very destructive "storm surge" of hurricanes, but we also will learn about the mighty tsunami generated by earthquakes.

Waves continue to fascinate everyone who walks along a beach or who sails in the ocean, and one of life's most pleasant memories is the sound of breaking waves and the feel of warm ocean water that runs up the beach and swirls around our feet. Sometimes the waves we observe appear to be very well organized, with distinct wave trains moving in the same direction; sometimes the sea appears chaotic with a surface that is ill-defined with waves appearing and disappearing. Sometimes the sea is angry, as shown in the picture on the right taken in the month of March, where I and my graduate students are attempting to launch a wave buoy in the ocean 150 km east of Cape Lookout off the NC coast. Such is the nature of this lesson.

 

 

Learning Objectives

At the end of this lesson, you should: (1) Be able to describe how wind waves may be limited from being fully-developed by wind speed, wind fetch, wind duration and water depth; (2) Explain why "white-caps" appear on wind waves in deep water and that they dissipate excess energy put into the ocean by the wind (3) Explain why and how wave dispersion creates order out of chaos and provides the best ocean swell on which to surf; (4) Explain why shoaling waves build-up and eventually break as depth decreases, and how the water motion under a surface wave, which in deep water is orbital, changes into more of a destructive horizontal movement; and (5) Explain the three ways in which waves change direction and why, if you are going to ride out a storm along a rocky coast, you would not want to anchor in a headland.

Reading Assignment

Garrison, OCEANOGRAPHY, An Invitation to Marine Science, 4th Ed. Chapter 10, pages 237-258.

Discussion

LESSON SUBDIVISIONS

To keep the timing of your learning consistent with the class schedule, this lesson has been divided into two parts. You may link to each below.

Part 1 contains discussions of the general wave characteristics and wave dispersion. CONTAINS AUDIO ELEMENTS

Part 2 contains discussions of a fully-developed sea. CONTAINS AUDIO ELEMENTS

Part 3 contains discussions of the shoaling and breaking of waves, and internal waves. CONTAINS AUDIO ELEMENTS

Part 4 contains discussions of the changes in wave direction. CONTAINS AUDIO ELEMENTS

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